OPTIMASI PERTUMBUHANKAPANG ENTOMOPATOGEN PENGENDALI WERENG COKLAT (Nilaparvata lugens Stal. (1853))DENGAN PENAMBAHAN BIOSURFAKTAN

NOVITA HARTATI, Prof. Dra. A. Endang S. Soetarto, M. Sc., Ph.D.,

2013 | Skripsi | BIOLOGI

Wereng coklat (Nilavarpa lugens) merupakan hama perusak tanaman padi yang menjadi masalah pertanian di Indonesia. Berbagai teknik pengendalian hayati dikembangkan untuk pengendalian wereng yang bersifat alami dan ramah lingkungan. Kapang entomopathogen telah dimanfaatkan sebagai agensia pengendali hayati serangga hama. Kapang tersebut menginfeksi serangga dengan melepaskan kitinase yang berperan untuk mendegradasi kutikula. Kematian serangga melalui aktivitas kitinase dapat ditingkatkan dengan penambahan biosurfaktan. Selain aktivitas enzim tersebut, kematian serangga terjadi karena toksin yang dihasilkan oleh kapang. Tujuan penelitian ini adalah meningkatkan aktivitas hidrolitik isolat kapang entomopathogen penghasil kitinase yang ditumbuhkan bersama dengan khamir penghasil biosurfaktan; memperoleh medium pertumbuhan yang tepat untuk menstimulasi isolat kapang membentuk spora; menguji sifat patogenisitas isolat kapang terhadap perkembangan nimpha wereng coklat Nilaparvata lugens. Penelitian dimulai dengan seleksi tiga isolat khamir penghasil biosurfaktan yang ditumbuhkan pada medium cair yeast extract ditambah minyak kelapa, diinkubasikan selama tujuh hari. Kemampuan untuk memproduksi bosurfaktan diuji secara kualitatif dengan Drop collapse test pada minyak kelapa.Isolat khamir penghasil bosurfaktan yang mampumengemulsi minyak kelapa dipilih. Hasil seleksi isolat khamir digunakan untuk memacu pertumbuhan isolat kapang untuk menghasilkan kitinase. Setiap interval waktu aktivitas kitinase dianalisis dengan menggunakan metoda DNS.Kemampuan tumbuh isolat kapang PL ditingkatkan untuk membentuk spora dengan menumbuhkan pada berbagai sumber karbon, yaitu gabah, kulit kerang, beras, jagung yang direndam ekstrak tauge dilengkapi dengan 2% sukrosa dan 1% peptone. Kemampuan membentuk toksin, isolat kapang PL penghasil kitinase diuji melalui metodeDisk diffusion pada kultur Bacillus subtilisyang ditumbuhkan pada medium Nutrient Agar. Toksin yang dihasilkan membentuk zona jernih disk. Bioassay dilakukan berdasarkan aktivitas kitinase dan toksin yang dihasilkan oleh salah satu kultur campur antara isolate khamir dengan fungi atau kultur tunggal jamur pada nimpha Nilaparvata lugens. Setiap interval waktu tertentu (0, 3, 7, dan 10 hari) jumlah nimpha mati diamati dan infeksi kapang pada nimpha diamati secara mikroskopi electron (Scanning Electron Microscope). Isolat kapang PL diidentifikasi berdasarkan karakter morfologi sel dan molekular. Hasil penelitian menunjukkan bahwa isolat khamir Y10.BS.016 mampu menghasilkan biosurfaktan yang mampu menstimulasi isolat kapang PL untuk menghasilkan kitinase yang mampu meningkatkan aktivitas kitinase sebesar 1.9 U/mL setelah 120 jam inkubasi. Pembentukan spora isolat kapang PL dengan jumlah yang tinggi terjadi pada media gabah yang direndam ekstrak tauge dilengkapi dengan 2% sukrosa dan 1% peptone. Hasil bioassay menunjukkan bahwa isolat kapang PL setelah tiga, tujuh, sepuluh hari inkubasi mampu membunuh nimpha masing-masing sebesar 0.67%, 5.33%, dan 0%; untuk kultur campuran isolate kapang dengan khamir sebesar 6%, 2%, dan 0%. Pengamatan SEM menunjukkan bahwa pertumbuhan hifa dan penempelan khamir terjadi pada integument wereng. Berdasarkan hasil analisis molekular, isolat kapang PL mempunyai karakter dekat dengan Paecilomyces lilacinus.

Brown planthopper (Nilaparvata lugens) is one problems in Indonesian agriculture because it’s a destructive insect pest of rice crops. Various biological techniques have been were developed to control insect pest naturally and having environmental friendly. Entomopathogen fungi have been used as biological control agents the insect pest. The fungus infected insects by releasing chitinase to degrade the cuticle. The chitinase activity could be accelerated by the addition of biosurfactants on the growth medium. Another factor that accelerates the death of the insect was a toxin produced by same fungi.The purposes of this study were to increase the hydrolytic activity entomopathogen fungi isolate to produce chitinase by growing them together with biosurfactant-producing yeast; to obtain the appropriate growth medium for stimulate spores produce by fungi; to test the pathogenicity of fungi isolate on development of brownplanthopper (Nilaparvata lugens) nymph. The research was commenced by of three isolates biosurfactant-producing yeast based on their to ability to grow on liquid yeast extract medium added with cocconut oilincubated for seven days. The ability to producing biosurfactants was test qualitatively using Drop Collapse Test. The biosurfactants producing yeast cultures able to emulsify coconut oil were selected. The selected biosurfactant producing yeast were used to stimulate the entomopathogen fungi to produce chitinase through a growth experiment. At an interval time, the growth mixed cultur was monitored based on the chitinase activity using DNS method. The ability of producing spores the isolate fungi enhanced by growing on various carbon sources, there are grain, sea shell, rice, and corn was mixed with bean sprouts extract, 2% sucrose, and 1% peptone. The toxicity of fungi isolate cultur was test using Disk diffusion method on Bacillus subtillis cultur grown on Nutrient Agar medium. Bioassay of fungi culture was carried out based on its chitinase activity and toxin produced by either mixed culture the yeast and the fungi or single cultur of fungi on nymph Nilaparvata lugens.Every an interval time (0, 3, 7, and 10 days) the number of dead nimpha was observed and the fungus infection were observed with electron microscope (Scanning Electron Microscope). The fungi isolate PL were identification performed by morphological and molecular character. The results of research revealedthat one of the yeast isolate Y10.BS.016 was able to produce biosurfactant which could be increase the fungi isolate PL was to produce chitinase,the chitinase activity increase until 1.9 U/mL after 120 hours incubation. The high spora formation of fungi isolate PL occur in grain medium mixed with bean sprouts extract be equipped of 2% sucrose and 1% peptone. The results of bioassay revealed that fungi isolate PL after three, seven, and ten days incubated could be kill nymph respectively 0.67%, 5.33%, and 0%; while the mix cultur fungi and yeast isolate was 6%, 2%, and 0%. Scanning Electron Microscope observation indicated that there was growth of hyphae and yeasts in the integument attachment pests. Based on the results of the molecular analyzed, fungi isolate PL has a simillar character with Paecilomyces lilacinus.

Kata Kunci : Kapang entomopathogen, biosurfaktan, kitinase, wereng coklat